More about part: LOMO / Bresser Biolam 40x 0.65 F-2 phase contrast microscope objective 1976 with RMS thread | Carl Zeiss Jena compatible (ID: 99524)

Description

LOMO microscope objective with 40x magnification, intended for second-type phase contrast and for use with the LOMO KF-5 condenser.

A very important note: two phase rings inside an objective bring to mind variable phase contrast (PhZ at PZO or PhV at Carl Zeiss Jena). With LOMO, however, this is rather something like a "second type of positive phase contrast". LOMO states in the manual ([[ LINK ]]) that one image is obtained when light passes through both rings (with the condenser iris diaphragm open) - and a different one when the diaphragm is closed far enough that light no longer reaches the outer, wide ring and only the inner ring works. The manufacturer recommends viewing the specimen in both modes, because together they give a more reliable idea of its structure. The contrast stays positive (thicker or denser parts of the specimen appear darker against a bright background), and both modes differ from work with the single-ring "Ф" objectives and the LOMO KF-4 condenser (ЛОМО KФ-4), where both the objective and the condenser diaphragm have only one ring. So the resulting effect does change - but this is not variable phase contrast; the change is stepwise (either-or), not continuous.

The objective presented here fits the LOMO KF-5 condenser (ЛОМО KФ-5). That condenser has a mounting diameter of 37 mm and is very often used on microscopes from other makers, among them Carl Zeiss Jena and Olympus (especially Olympus CH). With a suitable build-up ring fitted (3D printed, for example), this condenser is commonly used in microscopes with a 39,5 mm condenser seat as well. The instructions for setting up LOMO KF-5 phase contrast can be found here: [[ LINK ]]

This is a so-called short barrel objective, with a parfocal length of 33 mm. It is very commonly mounted on a 12 mm extension, which allows it to be used in microscopes that require objectives of 45 mm length. Professional adapters with protective optics, metal adapters and the popular 3D printed DIY solutions all work here.

LOMO objectives are very popular with owners of microscopes from other makers. Because of the historical links, owners of Carl Zeiss Jena microscopes treat them as an obvious substitute for those German objectives.

This objective fits practically any microscope from any maker, provided it has an RMS thread and accepts objectives with TL=160 mm and a parfocal length of 33 mm (or 37 / 45 mm if a suitable adapter is used). A few such microscopes are listed in the "compatibility" section, but that is not a complete list.